In a conventional organic light-emitting device, sealing is performed in a manner as shown in FIG. 12 of JP2009-134897A. An inert gas or the like is filled in an internal space, called a getter chamber, which is formed between a sealing plate and a glass substrate. A drying material is also arranged in the internal space. This helps prevent an organic light-emitting layer from making contact with external moisture or water.
However, the heat transfer to the sealing plate by the convection of the inert gas is very small, and the heat conductivity of an organic light-emitting layer and the glass substrate is low. This leads to an increase in device temperature because the low heat transfer and conductivity will lead to the retention of heat generated during the operation of the light-emitting device. In an organic light-emitting device such as an organic EL (electroluminescence) device or the like, the temperature of the light-emitting device is increased by so-called Joule heat, the heat generated by electric resistors within the light-emitting device. It is known that such temperature rise accelerates degradation of an organic thin film and separation of an electrode film, becoming a major cause of the reduction of the lifespan and performance of a light-emitting device. The light-emitting device results in a destructive cycle in that temperature rise leads to easy flow of a current which in turn results in temperature rise. The temperature rise is directly associated with the lifespan.
In view of this, as shown in FIG. 1 of JP2009-134897A, there is proposed a structure in which, for the purpose of enhancing heat dissipation, a heat transferring member is arranged between a sealing plate and a cathode layer to thereby dissipate heat.
In the prior art referred to above, however, the heat transferring member makes close contact with only the upper surface of the cathode layer with no provision of a space for the getter chamber. For that reason, heat dissipation is insufficient. Moreover, the drying material needs to be arranged in the getter chamber, which makes the manufacturing process complex and costly.